1. The Field of the Invention
The present invention relates generally to powered fastener drivers and particularly relates to an improved nail gun having a guide mechanism to facilitate accurate and consistent orientation and placement of nails as the nails exit the nail gun.
2. The Relevant Technology
In the endless pursuit of increased productivity, industry has continuously sought ways to improve worker effectiveness and efficiency. Many traditionally manual functions are now partly or fully accomplished by mechanized means. One of the major advances in the construction industry was the development of powered nail guns. These guns typically drive nails or other fasteners by means of a driving mechanism which, in turn, is impelled by compressed air, electrical power, or the like. Powered nail guns have numerous advantages, not the least of which is the ability to drive nails or other fasteners in a fraction of the time that would be required for a construction worker using a traditional hammer. Another important advantage of these guns is their ability to drive a variety of fastener types into a wide range of materials, such as concrete, steel, sheet metal, and wood.
While powered nail guns clearly provide significant advantages in terms of efficiency and versatility, the nail guns are not without their shortcomings. A major problem area concerns the inaccuracy and inconsistency of nail placement and orientation.
In order for nail guns to realize their maximum potential as effective and useful tools, they must be both accurate and consistent in their placement and orientation of nails. Nail guns that shoot nails inaccurately and/or inconsistently are a source of frustration at best, resulting in re-work and wasted production time. At worst, inaccurate and/or inconsistent nail guns can cause serious injury to the operator or to others near the work area; the high magnitude of the driving forces utilized by typical nail guns makes the problems of inaccuracy and inconsistency particularly dangerous.
The problems of inaccuracy and inconsistency in the placement and orientation of nails can manifest themselves in all types of nail guns and with all types of fasteners. However, these problems become especially acute when the nail gun is shooting relatively shorter nails, such as the nails typically used to secure metal joist hangers, ties, and straps; generally, these types of nails are approximately 11/4" to 21/2" in length.
A major cause of inaccuracy/inconsistency problems relates to the channel defined by the nose of the nail gun. The nose of the gun defines a generally U-shaped channel, inside the nail gun, through which the nails travel; typically, this channel is somewhat larger in diameter than the driven fasteners. As a result of the dimensional differences between the nails and the channel through which they travel, the nails have some freedom to move about inside the channel and thus are prone to tilt back and forth slightly or "tumble" as they are pushed down the channel. Generally, relatively shorter nails are more susceptible to tumbling than are relatively longer nails. Because the typical nail gun has no means to prevent the fasteners from tumbling, the nails tend to exit the nail gun in random orientations. Thus, the nail gun operator can never be completely assured that a particular nail will come out straight, or that the nail will enter the work piece at the point that the operator intended.
As noted earlier, inaccurate and inconsistent nail placement and orientation is, at best, problematic. However, when the operator is using the nail gun to drive nails through holes pre-drilled in metal items such as joist hangers and straps, inaccuracy and inconsistency present serious safety hazards. Specifically, the random placement and orientation of the nails that is typical of many nail guns, coupled with the high energy of typical nail gun drive mechanisms, causes some nails to miss the pre-drilled hole entirely, strike the metal, and ricochet dangerously away.
The dangers presented by inaccurate and inconsistent nail placement and orientation have not gone unrecognized in the field. Efforts have been made to resolve, or at least minimize, the possible effects of inaccurate and inconsistent nail driving when attaching metal members. However, as indicated in the following discussion, these prior efforts fail to completely and effectively resolve the problems.
At least one attempt to resolve the problem of inaccurate and inconsistent nail orientation and placement has placed the primary focus not on the nail gun itself, but rather on the material through which the nail is being driven. In particular, the material, typically sheet metal of some kind, is embossed in such a way that the embossment forms a funnel-shaped indentation centered about each of the holes pre-drilled in the sheet metal. The purpose of the funnel is to guide errant nails towards the hole as the nails exit the nail gun.
The embossed funnel approach is somewhat problematic however. First, it fails to correct the fundamental cause of the inaccuracy and inconsistency problems; that is, the tendency of the nails to tumble as they are being driven. Rather than preventing the tumbling problem, the funnel approach is focused at correcting the effects of tumbling after the tumbling has already occurred. More importantly however, this approach is disadvantageous because of the increased tooling and production costs involved with embossing the metal through which the nail is fastened. Finally, embossed metal fittings are essential to the success of this method; clearly, if the user does not have access to embossed metal fittings or if the fittings are unavailable for any reason, the problems of inaccurate and inconsistent nail placement will persist.
Another of the other attempts at resolving the inaccuracy and inconsistency problems in nail placement and orientation focuses on the nail gun itself. In this case, a specialized nail gun has been developed which allows the tip of the nail to be extended partially from the gun prior to driving. In this way, the user can place the tip of the nail in the hole, and then pull the trigger of the gun to drive the nail. This has proven to be a limited solution however.
The major shortcoming of this approach is that because the "protruding tip" nail gun is specially adapted for the particular purpose of driving nails in metal items, it is not suitable for other applications, such as framing. Thus, a contractor would be required to incur the additional, and substantial, expense of purchasing an extra nail gun for the sole purpose of attaching metal members such as joist hangers.
In view of the aforementioned problems with driving nails in metal members, what is needed is an improved nail gun that will provide both consistent and accurate nail placement and orientation, without requiring special modification of the work piece. Specifically, the nail gun should have a guide mechanism that would prevent the nails from tumbling as they are driven from the nail gun. Further, the guide mechanism should be readily adaptable and field mountable to a variety of conventional nail guns, so as to preclude the need for purchase of a specialized gun. Finally, the guide mechanism should have a pilot or the like to provide the operator with assurance that the gun is properly lined up with respect to the hole in the work piece.